Stereoscopy, or three dimensional imaging, relates to any technique that records three dimensional visual information and creates an illusion of enhanced depth in a user's perceived image. Traditional two dimensional images utilize human visual cues of occlusion of one object by another, convergence of parallel edges, change in size of textured patterns, haze, desaturation, shift to bluishness, and subtended visual angle. Stereoscopy enhances the illusion of depth in motion pictures, photographs, and other two dimensional images by presenting slightly different images to each eye, and thereby adding the human visual cue of stereopsis.
Glasses for viewing three dimensional images exist in two categories: active and passive. Among active 3-D glasses are liquid crystal shutter glasses and display glasses. Liquid crystal shutter glasses contain liquid crystal that blocks or passes light through synchronization with images on a computer display, using alternate frame sequencing. Stereoscopic head-mounted displays include one display per eye, which display a different perspective near each eye, and are not used in conjunction with an external screen to be viewed at distance. Some examples of active shutter glasses lens are controlled by infrared (IR), radio frequency (RF), DLP-LINK®, BLUE-TOOTH® TRANSMITTER and sent-timing signal which uses electronic component to receive signal from emitter connected to display to activate a light shutter with the frequency of 120 Hertz or 240 Hertz or more.
The active shutter glass lens needs to be in a dark room in order to realize better resolution and full stereoscopic sensation. Some people like this but some will feel uncomfortable as well as their eyes and brain will get tired in a longer period time over than 2 hours. Moreover, active shutter glass lens has high resolution but the flat shape of frame and heavier than usual weight, increase eye strain, eye pressure, and induce nausea and headache when wore over long periods of time. Using flat lens shape, such lenses do not match the natural curvature of the eye. Due to the flashing of stereoscopic images at 120 Hertz or more, it will cause greater eye discomfort without a lens curvature. This invention aims to create a lens curvature or cylinder for 3D glasses.
On the other hand, passive 3-D glasses include linearly-polarized glasses, circularly-polarized glasses, infitec glasses, complementary color analyphs, chromadepth method glasses, anachrome compatible color analyph glasses, and red-eye shutter glasses. Linearly polarized glasses are used when a stereoscopic motion picture is projected and superimposed on the same screen through orthogonal polarizing filters. The viewer wears glasses containing orthogonal polarizing filters, which only pass through similarly polarized light and block orthogonally polarized light, allowing the viewer to only see one of the images in each eye to achieve a 3-D effect. Viewers must keep their heads level in order to prevent bleeding of images from the left and right channels into the opposite channel.
A more advantageous passive 3-D method is the circularly polarized glasses which are used in circumstances where two images are projected superimposed onto a screen through circular polarizing filters of opposite handedness. The user wears eyeglasses which contain a pair of circular polarizing filters mounted in reverse, whereby light that is left-circularly polarized is extinguished by the right-handed analyzer and light that is right-circularly polarized is extinguished by the left-handed analyzer. This allows the user to tilt his head while viewing stereoscopic images and still maintain left and right separation.
Circularly polarized glasses have the advantage over linear polarized glasses because viewers with circularly polarized glasses may tilt their heads and look about without a disturbing loss of 3-D perception, whereas viewers using linear polarized glasses must keep their heads aligned within a narrow range of tilt for effective 3-D perception, or risk seeing double or darkened images. Currently circularly polarized glasses use flat lens that cannot match with the eyeball curvature. As a result, vision will not be optimal and eyes get tired easily. A further drawback of flat laminated lens is that after it is cut and curved to a specific shape with a certain eyeball curvature, the molecules would be rearranged in films again which further distorting the clarity. Therefore it is important to create a curvature of the lens without rearranging the molecules.
The current construction of flat lens for passive linear polarized glasses, passive circularly polarized glasses and active shutter glass lenses limits the frame shape and design, which contribute to heavy discomfort in the user's eyes and brain. Generally, polarized 3-D lenses require a polymer laminate to support the retarder film on the lens. A retarder is an optical device that alters the polarization state of a light wave traveling through it. Currently, materials used to fabricate retarder are by using flat sheet of PC (polycarbonate). The problem with flat sheet PC (Polycarbonate) is that it does not curve well, thus unable to conform to lens having curvature. By implanting the method of using PVA material to fabricate retarder of the present invention, it now becomes possible to make any retarder tailoring to curvature which has the consistent circulation variation. The new method of processing the retarder with new laminate technology improves the 3-D stereoscopic image. The linear polarized film or partially circular polarized film is glued to the retarder. The retarder is filled with gaping agent. The epoxy liquid is laminated outside the retarder then cured with air or UV light to create a 3-D circular polarized function card. The new function card will have a better birefrigent effect without extra polymer sheets, thus improving transmission. Currently state of the art allows for 60-85% transmission. Other inventions use polymer sheets to support the linear polarizer. The use of polymer sheet requires moist glue, which interferes with transmission. In our invention, the thinness of the PVA retarder film allows the application of almost crystallized lamination possible.
The present invention involves a process by which a thin PVA retarder and a circular polarizer may be produced and assembled with dry glue. This process allows the wearer to view stereoscopic images for a longer time period without discomfort. The process entails application of organic polyvinyl alcohol (PVA) as the ingredient to create retarder film which is a substantial improvement to current flat 3-D lenses. Other advantages of these methods versus previous methods include making distortion-free, thinner, flexible, functional, comparable, durable, optimal-performance circular polarized 3D lens. This innovative method allows for conforming the retarder film onto a lens shape when the retarder film is still malleable and moist rather than cutting the lens from a flat sheet of polymer.